Non-Return Valve . (299 & 399); Primary Secondary Piping; Circulator Functionality; Frost Protection - Slant/Fin VGH-299-CH Installation And Service Manual

NON-Return valve. (299 & 399)
Both boilers VGH 299 CH and VGH 399 CH have a non-return valve installed in the gas-air mixing pipe just before
the burner. Flue gas recirculation is prevented by the non-return valve. The prevention of recirculation also reduces
standby loses through the flue of the boiler. This creates a higher thermal efficiency.

Primary Secondary Piping.

The boiler has no internal bypass. The system must have primary secondary piping to allow an adequate flow.
One option for primary secondary piping is to use closely spaced tees spaced 4 pipe diameters apart and a
maximum of 12" apart. Another option for primary secondary piping is to use a low loss header for this function.
The boiler flow will also be influenced when a pipe of the heating system is frozen / blocked. Make sure all heating
pipes are free from the risk of frost. If there is the risk of freezing of the heating system, all the pipe section must
be insulated and/or protected with the help of a heat tracing.

Circulator functionality

Delta T monitoring:
A high temperature difference between supply and return of the boiler can indicate a clogged heat exchanger or
filter, or a defective circulator. The burner load automatically decreases when the Return/Supply temperature
differential increases too much.
At maximum burner power ∆T is limited to 72 °F and at low burner power a ∆T above 86 °F is not allowed.
Above these values the boiler modulates down until the temperature difference is between 72 °F and 86 °F.
If the ∆T exceeds 94 °F, the boiler will be temporarily switched off.

Frost protection

The boiler has a built-in frost protection that is automatically activates the boiler circulator when the boiler return
(water) temperature drops below 50 °F/ 10 °C (programmable). When the boiler return temperature drops below
the 41 °F/ 5 °C (programmable), the boiler is also ignited. The circulator and/or boiler will shut down as soon as
the return temperature has reached the 59 °F/ 15 °C (programmable). The mentioned temperatures are related to
the temperatures measured by the RETURN sensor of the boiler. This frost protection function will not fire up the
boiler in case of a "general blocking" of the boiler demand.
NOTICE: This "Frost Protection" function is only useable for the boiler and not for the whole central heating system.
Because it concerns a programmable setting, a boiler damaged by frost is not covered under warranty.

Installing a strainer and/or dirt separator

SYSTEM WITH DIRT SEPARATOR
WATER FLOW
FROM SYSTEM
SYSTEM WITH STRAINER
WATER FLOW
FROM SYSTEM
VALVE
STRAINER
(WITH FILTER)
SYSTEM WITH STRAINER AND DIRT SEPARATOR
WATER FLOW
FROM SYSTEM
VALVE
(WATER FILTER)
Figure 7. 6
DIRT
SEPARATOR
WATER FLOW
TO BOILER (S)
DIRT BLEED
VALVE
AIR BLEED
VALVE
WATER FLOW
TO BOILER (S)
VALVE
AIR BLEED
VALVE
DIRT
SEPARATOR
VALVE
STRAINER
E93.1601EN032.C VGH installation manual
Always install a Y strainer and/or a dirt
separator in the return pipe of the boiler;
in such a way that the water going to the
boiler is free of any debris/particles.
When using a Y strainer always check a
week after installation to determine the
strainer cleaning interval. Advice is to
mount valves before and after the
strainer, including an air bleed valve, so
the strainer can be isolated from the
heating circuit for service operations.
Clean water is very important, blocked
and/or
including
caused by this blockage are not covered
by the warranty. In existing systems
when replacing a cast iron boiler or
when installing in a system with cast iron
radiators or cast iron piping a magnetic
dirt separator must be installed.
WATER FLOW Its advised to place pressure measuring
TO BOILER (S)
gauges before and after the strainer.
Clean the strainer (water filter) when the
DIRT BLEED
VALVE
maximum delta P exceeds the value
prescribed by the strainer manufacturer.
polluted heat exchangers,
failures and/or damages
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